1. Field of Invention
The invention relates, generally, to a control device of a motor vehicle and, more specifically, to a such a device having an input equipped for processing signals of different types of sensors and a method for adapting the control device to a sensor that is to be connected to the control device.
2. Description of Related Art
A control device of a motor vehicle having an input equipped for processing signals of different types of sensors is known per se and has at least one input with an input port, at least two input channels, and an input circuitry. It is equipped to receive signals from a sensor via the input port and to transmit the signals via the input circuitry in an input channel of the input, which is connected to a defined voltage via a resistor. A method for adapting a control device of this type to a sensor that is to be connected to the control device is also known per se.
Control devices of this type process sensor signals and generate actuating variables therefrom, with which actuating elements of the motor vehicle are actuated to affect the behavior of the motor and/or components of the motor vehicle while in operation. As a result, operating parameters, for example, of the motor vehicle should be maintained within a permissible framework. The operating parameters are mapped thereby in physical variables that are detected by sensors and converted to electric sensor signals. Interfaces are necessary to transmit the electric sensor signals to the control device, which convert the sensor signals provided by a sensor into signals that can be processed by the control device. Different sensors require different interfaces thereby. As such, for example, analog interfaces, interfaces for “PWM” signals (PWM=Pulse-Width Modulation), frequency interfaces, and bus interfaces are known.
Normally, the interfaces are integrated in the control device and have an input port, input circuitry, and an input channel. Depending on which type of sensor is to be connected to the input port, the interfaces differ with regard to their input circuitry as well as with regard to the input channel.
With regard to the input circuitry, the inputs of control devices differ, for example, in whether the defined voltage has a comparably larger value (e.g., five volts) or a comparably smaller value (e.g., zero volts). In both cases, the defined voltage serves to determine a reference voltage with which, for example, error statuses can be detected. The connection to the comparably lower voltage is then carried out when the sensor works as a current supply. The connection to the comparably higher voltage is then carried out when the sensor works as a current sink. This is normally the case with a “PWM” sensor.
With regard to the input channel, there are, for example, the following differences: To process an analog signal, an input channel with an ADC (Analog/Digital Converter) is needed, for example, and to process a “PWM” signal, an input channel with a digital port is needed instead, ideally having a “capture/compare” function.
In the currently standard case, the number of (sensor) inputs of a motor-vehicle control device corresponds precisely to the number of sensors, the signals of which are to be processed by the control device. This number can differ even within a class of motor vehicles depending on the features of the individual motor vehicles. For example, many motor vehicles are equipped with halogen lights in the headlamps as the standard option. Motor vehicles of the same type can frequently be equipped with gas-discharge bulbs on demand, however, which provide a larger light flux. To prevent the blinding of other drivers, a headlight-range adjustment is usually provided with motor vehicles having gas-discharge lamps. This is the result of legal regulations requiring a headlight-range adjustment for headlights having a light flux of more than 2,000 lumen. Normally, a headlight-range adjustment of this type uses signals from inclination sensors that are, for example, disposed in the suspension of the motor vehicle and detect the inclination of the vehicle chassis. These sensors are frequently not included in motor vehicles of the same model that are equipped with halogen bulbs.
For financial reasons, it is increasingly attempted to standardize components, including control devices. The aim of a standardization of this type is that the standardized components within a class of motor vehicles can be used as frequently as possible without differences in their features making it necessary to use different hardware with the components. This applies analogously to different classes of motor vehicles. For this, certain constraints lead to different types of sensors, regardless of the vehicle, and a different number of sensors being used for one and the same function, e.g., for the automatic headlight-range adjustment. For automatic headlight range adjustment, there are solutions known, for example, using one, two, or three sensors. Depending on the design, these sensors are equipped to send analog output signals while other sensors are equipped to provide “PWM” signals.
From the possible differences in the number and type of the sensors to be connected to a control device, there are multiple different combinations of input signals of different types. A control device that can process these different combinations must be sufficiently flexible with respect to its hardware and software.
In the framework of the example of the headlight-range adjustment, it must be possible, for example, to connect both analog sensors and “PWM” sensors. In this context, a control device is given as known having two input channels for one input. For the implementation in a specific vehicle, the control device is furnished with an input circuitry that connects one of the two input channels with the input port of this input. In this manner, control devices of one type can be adapted to different vehicles, whereby, however, for each variation, one variant of a control device is needed. The different control-device variants differ from one another in the hardware of their input circuitry.
The equipping of control devices with input circuitry that is customized for different vehicle variants is complicated, and it also makes providing replacement parts more difficult. Both drive the respective costs up, whether it is for production or providing replacement parts. The introduction of control devices to the vehicle during its production is also more complicated because different vehicle variants are frequently manufactured on the same production line and it must, therefore, be ensured that each vehicle receives the right control device.
Thus, there is a need in the related art for a control device not having the aforementioned disadvantages. There is a need in the related art also for a method of the type specified above with which it is possible to avoid the aforementioned disadvantages.